Process for the clarification of lubricating oil additive concentrates



United States Patent() PROCESS FOR THE CLARIFICATION OF LUBRI- CATINGOIL ADDITIVE CONCENTRATES Alexander H. Popkin, New York, N. Y., assignorto Esso Research and Engineering Company, a corporation of Delaware NoDrawing. Application April 28, 1950, Serial No. 158,931

5 Claims. (Cl. 252-29) The art of lubricant manufacture is constantlysearching 1 for new methods, new processes, etc. to further raise thequality of their products.

Of particular rapid increase has been the over-all quality standards oflubricating oils such as gear oils, turbine oils, automotive engineoils, hydraulic transmission fluids and the like, those oils designed tomeet the stringcut and exacting requirements of high torque, high speedlubrication. In this particular phase of the lubricant art thedevelopment of new methods of refining and processing of petroleumfractions has been ment of lubricating oil additives. These lubricatingoil additive materials, when combined with the desired lubricating oilbases, further enhance the desirable characteristics of the lubricantcomposition. It is toward this particular segment of the art oflubricant manufacture, that is, the field of lubricant additives, thatthis invention is directed.

Among the long list of characteristics of lubricating compositions thatare improved by addition agents may be mentioned the rate of change ofthe lubricant viscosity with temperature, the temperature at which thelubricant loses its property of free flow, the lubricants resistance tooxidation, its resistance to shear breakdown, its ability to remainbetween moving metal parts at high temperatures and pressures, its lackof metal corroding properties, and many others. These improvements arebrought about by the addition to the lubricant base, either naturaloccurring oil stocks or synthetic oils, of small proportions of additivematerials which have been especially developed to improve one or more ofthese desired characteristics.

The additive materials or agents with which this invention isparticularly concerned are those additives which are added to thelubricant base in the form of an oil concentrate containing as little as5% or as much as 60% of the additive material. Thus, viscosity indeximprovers, pour point improvers, and the like are of primary concern inthe instant invention.

Among the lubricant additive materials that have been developed toimprove the viscosity index and pour points of lubricating oils may bementioned polymers of unsaturated hydrocarbons, such as isobutylene,butadicne, vinyl aromatics, and the like, polymers of acrylate andmethacrylate esters containing from 6 to 30 carbon atoms in the estercontributed portion of the molecule, copolymers oi? unsaturatedhydrocarbons such as isobutylene and isoprene or butadiene, styrene andisobutylene, styrene and butadiene, naphthalene and chlorinatedhydrocarbons, and the like. These additive materials are ordinarilyprepared as oil concentrates and as such are added to the lubricantbase.

In the preparation of the oil concentrates of the abovementionedadditive materials, considerable difficulty has been experienced in someinstances in that the additive concentrates have been found to be cloudyor semi-turbid in appearance. This cloudiness has been found to be theaided by the develop- 2,703,783 Patented Mar. 8, 1955 result of smallextremely finely divided particles which may not be removed by any ofthe known processes of filtration ordinarily used in the art.

Copolymers of isobutylene and isoprene or butadiene, prepared inaccordance with U. S. Patent 2,356,128 and known to the art as Butylrubber, and polymers of isobutylene, prepared in accordance with knownprocedures and having a molecular weight of between about 35,000 to50,000, are ordinarily increased in resistance to shear breakdown by aprocess of milling or extruding the prepared materials from a higher toa lower molecular weight. These processes are described in detail in U.S. Patents 2,239,501 and 2,466,300 for polyisobutylene and Butyl rubber,respectively. In the case of the milled polybutene the materials whichcause the cloudiness of the oil concentrates have been found to beextremely small discrete particles of carbon black, grease, metalfilings and the like, which have contaminated the polymer in the millingprocess. These contaminants have become dispersed in the milledpolybutene and are so small and so finely divided that they are notremovable by any known method of filtration, with or without the use offilter aids.

The cloudiness of the oil concentrates of Butyl rubber which has beenreduced from a higher to a lower molecular weight by the process ofextrusion described in U. S. Patent 2,466,301 has been found to be dueto a finely divided surface coating agent which is added to the Butylrubber prior to extrusion to prevent agglomeration of small particlesand aid in ease of handling in subsequent processing steps. This surfacecoating agent may be selected from a large number of known agents amongwhich are the metallic stearates, zinc stearate being the most commonand most widely used. When the extruded copolymer is admixed with thedesired oil to form the oil concentrates this intimately dispersed zincstearate, occurring in percentages of about 0.1% to 2.0% by weight,causes the oil concentrate to become cloudy or semiturbid. As was statedabove, this finely divided agent may not be removed from the oilconcentrate by any known method of filtration.

In the case of copolymers of styrene and isobutylene, which are usefulas viscosity index or pour point improvers, it is desired thatcopolymers having a styrene content of 25% or less be used. In themanufacture of this copolymer there is a certain amount of a higherstyrene content formed, for example, copolymers containing from about30% to 50% styrene. The cloudiness of the oil concentrates of thesecopolymers is due to the presence of this high styrene contentcopolymer.

Polymers and Copolymers of acrylate and methacrylate esters made withmethyl methacryiate as one component normally contain small percentagesof a polymer of methyl methacrylate. This methyl methacrylate polymer isbelieved to be the cloud former in the oil concentrates of the acrylateor methacrylate copolymer addition agents.

It has now been found, and forms the subject of this invention, thatthese cloud forming contaminants may be removed from oil concentrationsof these addition agents by an additional processing step prior to theordinary filtration step.

In general, this added step is accomplished in the following manner.

The oil concentrate of the addition agent containing from 5% to 80% ofthe additive material is heated to a temperature Within a range of fromabout 210 F. to 350 F. While at this temperature a gaseous aquophylicsubstance is passed through theoil concentrate for a period of timeranging from about 5 minutes to one hour. Although the exact mechanismof this processing step is not known, it is believed that the action ofthe aquophylic gaseous substance is such that coagulation oragglomeration of the small particles of contaminants occurs, theagglomerated particles being of sufiicient size as to be removable byfiltration.

As the gaseous aquophylic substance, it is preferred to use steam.However, other substances such as hydrogen chloride gas, ammonia gas,carbon dioxide, or mixtures of the above in any proportion may be used.

After the oil concentrate has been subjected to the action of theaquophylic gas for such time as is necessary to effect the desiredclarification, the treated oil blend which, at this stage is cloudy,both due to the agglomerated, insoluble contaminants and to the presenceof condensed moisture from the steam, may be dried by (l) blowing aninert gas through the heated oil blend, or (2) by adding a suitabledrying agent-filter aid, such as those diatomaceous earths sold undertrades names of HyFlo, Celite, Filter-eel, etc., familiar in the art.The resulting oil blend may then be filtered with the aid of the filteraid present through a suitable filtering medium. In some instances itmay be necessary to subject the filtered oil blend to a second treatmentwith the aquophylic gas although, in general, this can be avoided bysufficient treatment in the first instance.

The invention will be more clearly explained by a reference to thefollowing examples wherein steam is used as the aquophylic gas.

EXAMPLE I 500 gr. of a 20 weight percent concentrate in a phenol treatedMid-Continent distillate having a viscosity index of 108 and a viscosityat 210 F. of 36 S. U. S. of a copolymer of isobutylene and isoprene,prepared in accordance with U. S. Patent 2,356,128 and reduced inmolecular weight in accordance with U. S. Patent 2,466,300, was dividedinto two portions. One portion was filtered through HyFlo and the otherportion was raised to a temperature of about 250 F. and blown with steamfor minutes followed by filtration through a filter aid knowncommercially as HyFlo. Heliger turbidimeter and visual observationreadings were taken on the two samples and are reported in Table Ibelow.

It is to be seen that the steaming treatment followed by filtrationremoves substantially all of the turbidity from the oil concentrate, theturbidimeter reading decreasing 70 units.

EXAMPLE II About 300 gr. of a average molecular weight of about 32,000Staudinger, obtained by milling a copolyrner of isobutylene having amolecular weight of about 70,000 Staudinger according to the process ofU. S. Patent 2,239,501 was blended to a concentration in a phenolextracted Mid-Continent distillate having a viscosity index of 108 and aviscosity at 210 F. of 36 S. U. S. This concentrate was divided into twoportions. One portion was filtered through a filter aid, knowncommercially as HyFlo, and the other was heated to a temperature of 250F., submitted to the action of steam for about 15 minutes and thenfiltered through activated clay. Turbidimeter readings are reported inTable II below.

polymer of isobutylene having an r The utility of the process of thisinvention is remarkedly apparent in this example since the slightly hazyconcentrate after the filtration step showed the turbidimeter reading of22 and this haze was almost completely removed by the process of thisinvention, the turbidimeter reading being reduced to 6.

To summarize briefly, this invention relates to a process for theclarification of oil concentrates of lubricating oil additives which areordinarily turbid or cloudy which comprises the steps of subjecting theoil concentrate to the action of an aquophylic gas, preferably steam, athigh temperatures followed by filtration through a filter aid. Althoughsteam is the preferred gaseous treating medium, other aquophylic gasessuch as carbon dioxide, ammonia, hydrogen chloride gas, or mixtures ofthe above with steam are equally operable. The invention has particularadvantage for removal of zinc stearate from oil concentrates ofcopolymers of isobutylene and isoprene, commonly known as Butyl rubber,and for removal of small proportions of impurities from oil concentratesof polyisobutylene which have been reduced from high molecular weight toa lower molecular weight by a milling or extruding process.

What is claimed is:

1. A process for the clarification of oil concentrates of a polymericlubricating oil additive material selected from the class of polymers ofiso-butylene and copolymers of isoprene, said oil concentrates beingclouded due to the presence of a material of the class consisting ofzinc stearate and carbon black, which comprises heating the oilconcentrate to a temperature within a range of from about 210 to about350 F., subjecting the heated concentrate to the action of steam forfrom about 5 minutes to about 1 hour and filtering said heated steamedconcentrate to obtain a clear, unclouded solution.

2. A process according to claim 1 wherein said polymeric material is acopolymer of iso-butylene and isoprene and wherein said material of theclass is Zinc stearate.

3. A process according to claim 1 wherein said polymeric material is apolymer of iso-butylene and wherein said material ofthe class is zincstearate.

4. A process according to claim 1 wherein said polymeric material is acopolyrner of iso-butylene and isolpgfenle and wherein said material ofthe class is carbon 5. A process according to claim 1 wherein saidpolymeric material is a polymer of isobutylene and wherein said materialof the class is carbon black.

References Cited in the file of this patent UNITED STATES PATENTS1,564,501 Weir Dec. 8, 1925 1,603,174 Weir Oct. 12, 1926 1,769,766Bryant July 1, 1930 1,856,934 Stafford May 30, 1932 2,090,741 ZublinAug. 24, 1937 2,234,111 Doyle Mar. 4, 1941 OTHER REFERENCES Reprintedfrom The Science of Petroleum," published by the Oxford UniversityPress, around 1938; pages 1680, 1681, and 1685 pertinent.

Chemical Refining of Petroleum, by Kalichensky et al.; Reinhold Pub.Co., 1942, page 244 pertinent.

1. A PROCESS FOR THE CLARIFICATION OF OIL CONCENTRATES OF A POLYMERICLUBRICATING OIL ADDITIVE MATERIAL SELECTED FROM THE CLASS OF POLYMERS OFISO-BUTYLENE AND COPOLYMERS OF ISOPRENE, SAID OIL CONCENTRATES BEINGCLOUDED DUE TO THE PRESENCE OF A MATERIAL OF THE CLASS CONSISTING OFZINC STEARATE AND CARBON BLACK, WHICH COMPRISES HEATING THE OILCONCENTRATE TO A TEMPERATURE WITHIN A RANGE OF FROM ABOUT 210 TO ABOUT350* F., SUBJECTING THE HEATED CONCENTRATE TO THE ACTION OF STEAM FORFROM ABOUT 5 MINUTES TO ABOUT 1 HOUR AND FILTERING SAID HEATED STEAMEDCONCENTRATE TO OBTAIN A CLEAR, UNCLOUDED SOLUTION.